UK automotive workers union Unite has called on the makers of the iconic London taxi, Manganese Bronze, which is in the process of appointing administrators, “to do everything possible to secure a future for this manufacturer which is an iconic part of Britain’s manufacturing heritage”.

Unite national officer for the car industry, Roger Maddison said: “The London taxi is iconic and the staff who build them are highly skilled. The black cab is part of Britain’s car manufacturing heritage and we expect the company and the administrators to do everything possible to secure the future of this Coventry based company.

“Unite has met with the senior management today and the union has pledged to assist staff and the company to support a swift resolution to the current funding gap.

“Manganese Bronze is the last car manufacturer left in Coventry. If it becomes necessary the government should step in to support the company and protect the highly skilled workforce.” The firm employs 300.

Manganese Bronze on Monday called in administrators PricewaterhouseCoopers after failing to secure new funding.

A BBC report said the appointment followed the suspension of its shares earlier this month after a fault with the latest taxi’s steering box led to over 400 of them being recalled.

Last week, Managnese Bronze was reported to be trying to persuade 20% shareholder Geely – which builds the London Taxis under licence for China and other markets – to inject cash into its business thought this was apparently news to one top executive.

The UK taxi maker has booked losses for the past four years and, earlier this month, also stopped sales of its new TX4 model after power steering problems arose with a new design for the steering box, sourced from an unnamed new supplier since February. Some media reports had said Geely influenced the change of supplier and the BBC said the supplier was “a Chinese firm introduced by Geely”.

The company told the BBC it had not put anyone in danger but “in extreme cases, it could affect the ability to steer the steering wheel”.

It said in a statement that “the board remains hopeful that the fundamental strengths of the company, the TX4 model and its global reputation will provide the platform for a successful business in the future”.

Manganese and Geely signed a joint venture agreement in 2006 and own the factory in Shanghai that produces taxis for the international market.

The company was already in some financial difficulty before the latest problem emerged.

Sales have been in decline – the Coventry-based firm sold 1,502 taxis in the UK last year, compared with 1,653 in 2010, a fall of 9.1%, the BBC said.

In January, Manganese Bronze had to issue a profit warning, saying that it had made no profit in 2011 and could fall short of expectations this year.

The group blamed the weak UK economy, uncertainty over the global economic outlook and a delay in fulfilling an order for 1,000 taxis from Azerbaijan.

For the first six months of 2012, Manganese Bronze recorded an operating loss of GBP3.1m on revenues of GBP34.3m, the BBC said.

Then in August, it discovered an accounting error had caused it to understate past losses by a total GBP4.25m.

UK asset manager Toscafund owns 25% of the shares.